Netiquette

Community sites

General Portals

LinuxGizmos.com - the canonical (no pun intended) place for news about embedded Linux (and the successor to the now-inactive LinuxDevices.com, which is now available as a static, searchable 15,000 page archive)

Communities for beginners

Embedded Systems Common Technical Baseline - Although not directly related to Linux this site is an excellent overview of what embedded systems are seen from various angles (hardware, software, design methods, etc...)